Add test to command tables

[dgarcia360]

Command tables do not have unit tests. To solve this issue, we can move existent tables to a new views folder, and implement unit tests for every table.

[decentraliser]

Do you want to add more tests to tables? Such as signed transactions, or edge cases (no mosaics, etc)?

IMO it is already OK like that

[dgarcia360]

I would like to add tests to tables such as: https://github.com/nemtech/nem2-cli/blob/master/src/commands/metadata/account.ts#L34-L59 It might make sense to move them under the views folder as well.